Fair Value (Reconciliation For All Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Significant Unobservable Inputs (Level 3)) (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2015
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		$ (25,337)	$ (16,470)	$ (23,758)	$ (16,435)
Included in net income		0	0	0	0
Included in other comprehensive income		0	0	0	0
Included in regulatory assets/liabilities	[1]	(1,506)	5,087	(6,937)	9,309
Purchases		0	0	0	0
Issuances		0	0	0	0
Settlements		1,257	676	5,109	(3,581)
Transfers from other categories		0	0	0	0
Ending Balance		(25,586)	(10,707)	(25,586)	(10,707)
Natural Gas Exchange Agreements [Member]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value						$ 817
Natural Gas Exchange Agreements [Member]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance			(2,418)	(35)	(1,219)
Included in net income		0	0	0	0
Included in other comprehensive income		0	0	0	0
Included in regulatory assets/liabilities	[1]	(8,163)	235	(7,386)	2,084
Purchases		0	0	0	0
Issuances		0	0	0	0
Settlements		521	0	596	(3,048)
Transfers from other categories		0	0	0	0
Ending Balance		(6,825)	(2,183)	(6,825)	(2,183)
Power Option Agreement [Member]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		(251)	(428)	(424)	(775)
Included in net income		0	0	0	0
Included in other comprehensive income		0	0	0	0
Included in regulatory assets/liabilities	[1]	106	(177)	279	170
Purchases		0	0	0	0
Issuances		0	0	0	0
Settlements		0	0	0	0
Transfers from other categories		0	0	0	0
Ending Balance		(145)	(605)	(145)	(605)
Power Exchange Agreements [Member]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		(25,903)	(13,624)	(23,299)	(14,441)
Included in net income		0	0	0	0
Included in other comprehensive income		0	0	0	0
Included in regulatory assets/liabilities	[1]	6,551	5,029	170	7,055
Purchases		0	0	0	0
Issuances		0	0	0	0
Settlements		736	676	4,513	(533)
Transfers from other categories		0	0	0	0
Ending Balance		$ (18,616)	$ (7,919)	$ (18,616)	$ (7,919)

[1] Natural Gas Exchange Agreement Power Exchange Agreement Power Option Agreement TotalThree months ended June 30, 2015: Balance as of April 1, 2015$817 $(25,903) $(251) $(25,337)Total gains or losses (realized/unrealized): Included in net income— — — —Included in other comprehensive income— — — —Included in regulatory assets/liabilities(8,163) 6,551 106 (1,506)Purchases— — — —Issuance— — — —Settlements521 736 — 1,257Transfers to/from other categories— — — —Ending balance as of June 30, 2015$(6,825) $(18,616) $(145) $(25,586)Three months ended June 30, 2014: Balance as of April 1, 2014$(2,418) $(13,624) $(428) $(16,470)Total gains or losses (realized/unrealized): Included in net income— — — —Included in other comprehensive income— — — —Included in regulatory assets/liabilities235 5,029 (177) 5,087Purchases— — — —Issuance— — — —Settlements— 676 — 676Transfers to/from other categories— — — —Ending balance as of June 30, 2014$(2,183) $(7,919) $(605) $(10,707)Six months ended June 30, 2015: Balance as of January 1, 2015$(35) $(23,299) $(424) $(23,758)Total gains or losses (realized/unrealized): Included in net income— — — —Included in other comprehensive income— — — —Included in regulatory assets/liabilities(7,386) 170 279 (6,937)Purchases— — — —Issuance— — — —Settlements596 4,513 — 5,109Transfers to/from other categories— — — —Ending balance as of June 30, 2015$(6,825) $(18,616) $(145) $(25,586) Natural Gas Exchange Agreement Power Exchange Agreement Power Option Agreement TotalSix months ended June 30, 2014: Balance as of January 1, 2014$(1,219) $(14,441) $(775) $(16,435)Total gains or losses (realized/unrealized): Included in net income— — — —Included in other comprehensive income— — — —Included in regulatory assets/liabilities2,084 7,055 170 9,309Purchases— — — —Issuance— — — —Settlements(3,048) (533) — (3,581)Transfers from other categories— — — —Ending balance as of June 30, 2014$(2,183) $(7,919) $(605) $(10,707)